Extension Educator, Local Food Systems and Small Farms
Extension Educator, Horticulture
May 28, 2008
It has definitely been another unusual year weather wise. Of course I could really make a case for there really not being a "usual" weather pattern anymore, but rather an average of extremes. We are probably running a good two weeks behind normal in development and temperature.
We do have the first May/June beetles out for the year. These insects come from grubs in the lawn or garden. This brings us to the first frequently asked question of the week: "When do I treat for grubs?" To start with, there are several types of grubs. There are several types of grubs. There are the annual white grubs, true white grubs, Japanese beetle grubs, and green June bug grubs. There are others, and these are called by many names as well, but this will suffice for the discussion today.
All these beetles have a larvae called a grub, and have a complete life cycle. The cycle goes egg, larvae, pupa, and adult. I mentioned seeing the first adults of the season of the May beetle. I also found several Japanese beetle larvae while planting some flowers. The larvae of the Japanese beetles will be with us for a few more weeks before they pupate. Then of course the actual beetle stage follows the pupa. What this really means is we are in a rotten time to try and treat the larvae (grub) stage. The May beetles will have all the eggs hatched out by the end of July, and the Japanese beetle larvae will be around the third or fourth week of August.
The old timing (before the Japanese beetle) for grub control was around the Logan County Fair. This allowed all the eggs to hatch out into grubs before the treatment was applied. The grubs were also small at the time, and smaller grubs are easier to control than the large ones. Now with the Japanese beetles covering most of the county, it is recommended to treat around the end of August to allow all those eggs to hatch.Many products say they can be applied in the spring to control grubs all season, and they will when they first come on the market. Over time, microbes that break the chemicals down build up in population. When this happens, the products can no longer provide long periods of control. History is full of cases of insecticides no longer being effective because of microbial degradation. I'll cover the products available for application when the correct application timing draws near.
May 28, 2008
It's another year of very high tick populations. Probably, the frequent spring rains in much of the state have provided the high moisture and humidity that ticks need. Ticks are large, flattened mites that feed as parasites on mammals, birds and reptiles. They hatch from eggs into six-legged larvae that locate hosts and feed before dropping off the host and molting into eight-legged nymphs. Nymphs locate hosts, feed and drop off to molt into eight-legged adults. Adults also locate hosts on which to feed. Males may stay on the host, mating with females coming there to feed. Females engorge on blood to several times their original size, drop off the host and lay hundreds of eggs. With each tick having to find three hosts in its lifetime, many ticks starve before reproducing, although ticks can survive for long periods without food.
Ticks are numerous in areas of tall grass, where humidity is high and hosts common. Mowing greatly reduces tick numbers. When walking or working in areas of tall grass or other areas with ticks, apply a repellent containing about 30% DEET, such as Off or Cutters, to the lower legs and pants legs. If ticks are numerous in mowed areas, spraying carbaryl, permethrin, or bifenthrin should help give some control.
If a tick is attached, grasp the head with tweezers where the mouthparts enter the skin, pulling slowly and consistently. The tick will release its mouthparts and come loose. Do not handle the tick. Other methods such as heat and nail polish commonly kill the tick, resulting in locked mouthparts that remain in the wound to cause infection. A tick typically feeds for 24 hours before releasing disease organisms; remove ticks promptly when you find them.
May 20, 2008
Application of imidacloprid (Merit and other brand names) and other systemic insecticides is effective in controlling Japanese beetle adults. Although the imidacloprid occasionally doesn't work in a tree to control this pest, it does over 80 percent of the time. However, a soil application of imidacloprid typically takes 6-8 weeks to move completely up to the leaves of large trees. With Japanese beetle emergence typically starting the fourth week of June in our area, time is quickly passing to achieve control in that manner. This would be a prime option for linden trees, crabapples, rose bushes, and other favorites of the Japanese beetle.Imidacloprid can be soil-applied either as a drench or by injection. Because imidacloprid is easily tied up on organic matter, mulch and other dead organic matter must be removed from around the base of the tree before a drench application is made. Removal of turf around the tree would also be recommended for a drench. Soil injections should be made deep enough to get below mulch, turf thatch, and other organic matter, but not deeper than 3 to 4 inches. Apply to the soil within 1 to 2 feet of the trunk, where the greatest concentration of fine feeder roots is located.
May 20, 2008
Anthracnose starts as dead leaf areas between leaf veins, or on the tips of leaves. When severe enough, leaves will fall. The good news is that it rarely harms trees. If enough leaves drop, a new set comes out in 4-6 weeks and we start all over. The next set of leaves may also get the disease, but they may not. Treatments when you see the symptoms of this disease are simply wasted time and money.
Apple scab is a similar disease that can cause premature leaf drop in apples and crabapples. The same scenario applies here. If you are on a regular spray schedule for fruit trees, it should prevent most of the problems. You could also spray crabapples this way, but you would have to weigh the cost and benefit since no fruit production is involved.
Plum pockets is caused by a fungus on trees in the stone fruit family. This would include mainly peaches and plums. It is rather striking with the bright red swellings on the green leaves. This disease can only be prevented with a dormant time application of a fungicide on your trees. Seeing it now means that you probably should have sprayed before the buds began to swell (meaning before leaves actually came out).What's the end result? Trees get leaf diseases each year. Very rarely are any trees killed by these problems, and those that die are usually one foot in the grave to begin with. The only things that help the trees at this point is fertilizing moderately and watering during extended dry spells (which might be a while!). The fertilizer helps trees cope with some of the lost energy from lost leaves and the effort to put out a new set.
May 20, 2008
The mosquito season has started in earnest. Of course mosquitoes aren't pleasant to begin with, but throw in the West Nile Virus, and many people are rightly concerned about West Nile Virus and how to control mosquitoes. For now, if you are using a program in stagnant water, with no fish, the wiggler stage is present and controls such as the B.t. israelae should be started. Also continue to remove development sites such as standing water, old tires, and other containers that hold water. The B.t. israelae can be applied to areas you can't drain, and it won't affect people, pets, or livestock.
May 12, 2008
Few things strike fear in the hearts of tree owners like the mention of borers. Borers are most often the larvae of beetles or moths, and they do their damage where you can't see it. The eggs are laid on or under the bark, and the small hatchling chews through to the part of the tree they feed on. They spend almost their entire lives inside the tree, where they can't be seen or controlled.
May 20 to 26 has been selected as Emerald Ash Borer Awareness Week because it coincides with the time of year that the adult beetles will begin to emerge. These borers have gotten a lot of press this past year. They are metallic green, about a half inch long, and make "D" shaped exit holes (unlike the ash borers we have had around here for many years which make "O" shaped holes).
Most borers are named for their primary target, but they also affect other species of trees and shrubs. As an example, the flat-headed apple borer can also affect pin oaks and about 15 other species. Many borers leave a tell-take hole in the trunk, but some such as the ash borer are weak and have to enter through a pruning or mechanical injury.
Painted Hickory Borer has been a common nuisance pest the past week. These borers attack dead and dying trees and firewood. They are not usually a concern in healthy trees. They look very similar to the lilac borer, but the lilac borer adults are out in the fall.
Here is a listing of common borers and their control times: Ash borers (early June and early July), Bronze birch borer (mid May and repeat two times at two week intervals), Dogwood borer (mid May and mid June), Flatheaded apple borer (late May and repeat in three weeks), Lilac borer (early June and early July), Locust borer (late August and mid September), Mountain ash borer (early June and mid July), Peach tree borer (mid June and mid July), Viburnum borer (early June and early July), and Zimmerman pine moth (April or August). The Emerald ash borer, although not confirmed in our area at this time, control time in Michigan begins mid May and runs through mid July.
You can see borer control isn't an exact science. Treatment times and re-applications are hopefully timed to catch the hatching eggs on the outside of the trunk, or discourage the adults from laying eggs. Some new research shows that trees that are under stress give off a certain pheromone that attracts more borers to the tree. So, keeping your trees in good growing shape will go a long way to helping the situation. Fertilizing with the same rate of broadcast fertilizer used for lawns will help (apply it early May and early September), and watering during extreme dry periods as well (with an inch of broadcast water per week.
The product of choice for many borers is now permethrin, since Dursban is off the market. Imidacloprid is fairly new on the market. One trade name is Merit (sold for homeowners as Bayer Advanced Garden Tree and Shrub Insect Care). This product use rate is an ounce per inch of circumference of the tree trunk. You then mix it with three gallons of water and pour around the base of the tree. It may take a few months for it to translocate though the tree. A good time to apply it is in early spring when the sap rises. These treatments need to be completed by late May to have a chance of getting the current season borers. Each treatment lasts about a year. Fruit trees generally are treated differently with Sevin, or just using the regular spray program due to the possibility of residue in fruit
Zimmerman pine moth is one of those "kind of borers." It generally affects only severely weakened trees, and goes just under the bark to girdle the cambium layer. It seems like older Scotch, red, and Austrian pines are favorites when they begin to decline. Bird damage from yellow bellied sapsuckers on trunks and main limbs also looks like borer damage to many. This bird damage is easily recognized by the evenly spaced holes in a straight line.
May 6, 2008
We have reached the heat units now for garlic mustard to elongate from a rosette, and begin to bloom. Garlic mustard is considered an invasive species, and some states have declared it a noxious weed. Illinois hasn't declared it such, at least not yet. The problem with garlic mustard is how quickly it spreads. It spreads so quickly it tends to choke out much of the desirable undergrowth in timber areas.
Garlic mustard is a cool season biennial herb with stalked, triangular to heart-shaped, coarsely toothed leaves that give off an odor of garlic when crushed. First-year plants appear as a rosette of green leaves close to the ground. Rosettes remain green through the winter and develop into mature flowering plants the following spring. Flowering plants of garlic mustard reach from 2 to 3-1/2 feet in height and produce button-like clusters of small white flowers, each with four petals in the shape of a cross.
Control of garlic mustard is somewhat difficult. Seeds can remain viable for at least five years in the soil. Small amounts can be pulled up (including the roots). Garlic mustard can re-grow from root material. For herbicides, glyphosate (Roundup) is the most often recommended. Remember glyphosate kills broadleaves and grasses it gets on. There has been some success with 2,4-D LV400 where there aren't concerns with other understory plants. Very large patches have been controlled with fire, but that completely destroys the understory of timbers. Remember to monitor areas for at least five years due to the seed dormancy period.Some action at this early time may help prevent larger problems down the road. It is much easier to control small patches than large ones.
May 6, 2008
Egg hatch may be running as much as three weeks later than normal. Of course, with the crazy "spring" we've had, the insects are probably somewhat disoriented as well.
After hatching, the caterpillars create a white, silken tent in the branch crotches of crabapple, hawthorn, mountain ash, flowering cherry, and other trees and shrubs in the rose family. Eastern tent caterpillar is one of the earliest defoliators. The feeding damage does not kill the tree, but it does use some of the stored energy of the tree. To answer the eternal question "What happens if I don't do anything?" I would simply respond forest trees are attacked every year, and they survive the onslaught.Control at this time can be accomplished by removing the tents, and the caterpillars inside, and taking a long way from the tree to dispose of. When caught early, the caterpillars tend to stay in the nest. As they grow, they will not be in the nest as much. Control with sprays of B.t., acephate, permethrin, carbaryl, etc. will also work.
May 6, 2008
May 5, 2008
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